The present invention relates to a friction reducing coating for engineering works, and, a soil adhesion-preventing sheet pile or steel tubular pipe with the same applied thereto and a soil adhesion-preventing construction method, a negative friction cut construction method, caisson construction method or pipe jacking construction method using the same.
More particularly, it relates to a friction reducing coating for engineering works which, when applied in advance to steel materials for temporary works to be extracted and recovered after completion of the works, such as sheet piles frequently utilized in underground excavation, underground foundation structure laying and the like utilizing shoring walls, prevents soil from adhering to the steel materials for temporary work after extraction, to a soil adhesion-preventing sheet pile and a soil adhesion-preventing steel tubular pipe, each coated in advance with the friction reducing coating for engineering works, and to a soil adhesion-preventing construction method which comprises using the friction reducing coating for engineering works and/or the soil adhesion-preventing sheet pile or steel tubular pipe.
It also relates to a friction reducing coating for engineering works which, when applied in advance to substrates, such as various tanks, water storage tanks and so forth, in applying a caisson construction method for laying such substrates underground in laying various foundation structures underground or, when applied in advance to such substrates as various Hume pipes, steel pipes or steel pipe piles in applying a pipe jacking construction method for laying such substrates underground (horizontally or vertically), reduces the friction between the various foundation structures and the ground, prevents the foundation structures from being damaged due to ground subsidence or changes in surrounding ground conditions and reduces the friction between the substrate surface and the soil to thereby make it easy to lay the substrates underground (speedup of laying, reduction in pushing force, etc.), and to a negative friction cut construction method, caisson construction method or pipe jacking construction method for laying foundation structures which uses the above-mentioned friction reducing coating for engineering works.
In the present invention, the term of xe2x80x9cengineering worksxe2x80x9d especially relates to xe2x80x9cconstructional engineering worksxe2x80x9d which means all types of constructional (erecting of buildings, parts of buildings and the like) work beneath the soil surface, such as placing and fastening substrates in the underground (soil). The term of xe2x80x9ca negative frictionxe2x80x9d means the friction between the structure laid underground and the surrounding ground (soil) and by which the structure are damaged in case of the ground subsidence in the surrounding, for instance. The term of xe2x80x9ca negative friction cut construction methodxe2x80x9d means that a building method wherein at least one substrate or part of a substrate is placed and fastened in the underground in a manner wherein the friction between the substrate surface and the soil material of the underground is reduced.
In foundation and like works in the field of construction and engineering works (civil engineering), it has been earnestly desired that the equipment, expenses and days required for the works be curtailed to thereby improve the work efficiency and that such troubles as damages to the foundation structures laid in the ground, which require much labor for repair or restoration, be prevented from occurring. If improvements are achieved in these aspects, it will become possible to curtail the foundation work cost and finish the works speedily.
In such and like foundation works, the art has so far encountered the problem that soil in the ground adheres to and is carried by temporary work steel materials such as sheet piles frequently used in underground excavation, underground foundation structure laying and the like utilizing shoring walls when those steel materials are extracted and recovered.
Such recovered temporary work steel materials (e.g. sheet piles) with soil adhering thereto produce problems, for example {circle around (1)} they create voids in the ground, hence the ground may be distorted and ground subsidence or the like may occur, possibly resulting in damages to the neighboring structures, {circle around (2)} much labor and cost are required to backfill for preventing the troubles mentioned above under {circle around (1)}, {circle around (3)} the steel materials after recovery can hardly be piled up in parallel, so that temporary storage thereof after recovery becomes difficult and {circle around (4)} since it is a precondition that such temporary work steel materials are reused after recovery, it is necessary for a constructor to pay the cost of washing if soil remains sticking to the temporary work steel materials when these are returned to a leasing company. Under the existing circumstances, it is therefore a general practice for a constructor to remove the adhering soil manually or pay high washing expenses to a leasing company.
To solve these problems, such technologies as mentioned below have so far been proposed.
First, JP Kokai Publication Hei-06-71241 proposes a mud-removing line (equipment) for sheet piles which comprises {circle around (1)} a mud removing apparatus, {circle around (2)} an earth discharging apparatus and {circle around (3)} a water washing apparatus and JP Kokai Publication Hei-06-330521 proposes {circle around (1)} an apparatus for removing earth and sand from sheet pile sections which comprises a rotary section for a wound wire and an air spraying section. However, both fail to essentially solve the soil adhesion problem since {circle around (1)} both require the installation of novel apparatus and {circle around (2)} the soil removing work itself is still necessary although the efficiency of the sticking soil removing work may be improved.
In JP Kokoku Publication Sho-61-47253, JP Kokai Publication Sho-60-175628 and JP Kokai Publication Hei-03-279516, it is proposed that a sticking soil scraper matched to the shape of sheet piles be buried adjacently thereto after excavation but before pile extraction so that the buried pipes and the like may be prevented from being deformed by the soil adhering to the sheet piles when these are extracted.
However, this method has problems, for example {circle around (1)} the soil remaining in the gap between the scraper and sheet pile cannot be prevented from sticking to the piles, {circle around (2)} the soil adhesion above the scraper cannot be prevented from sticking to the piles since the scraper is buried relatively lower and {circle around (3)} time and labor are required for making and placing the scraper matched to the shape of sheet piles.
JP Kokai Publication Hei-03-244711 discloses a method of preventing ground subsidence by extraction of shoring members which comprises filling a solidifying pourable material into voids formed upon extraction of the shoring members. However, this method according to which a roughly U-shaped thin sheet is attached to each shoring member at its lower end and left in the ground when that member is extracted and a solidifying pourable material is poured into the voids after extraction to thereby prevent ground subsidence still has room for contrivance for producing such effects more simply, for example by applying a coating to the surface of temporary work steel materials or the like in advance.
JP Kokai Publication Hei-06-71241 discloses a method of removing mud from sheet piles which comprises piling up and supporting a large number of sheet piles with a U-shaped section with the opening side above at a level higher than a treatment line, allowing the lowest stage sheet pile to fall and feeding the same in the lengthwise direction, cutting off and removing the adhering mud from the internal circumference surface and external circumference surface during feeding, then washing the internal and external surfaces by spraying with a washing liquid and, thereafter, discharging the sheet pile from the treatment line. However, even such method has room for contrivance for removing mud from sheet piles or the like more efficiently, for example by applying a coating to the surface thereof in advance.
As explained hereinabove, there is no method available in the art for the prevention of soil adhesion by a simple procedure independent of the shape of buried temporary work steel materials and with almost no soil sticking (adhesion) to the temporary work steel materials after extraction so that the washing thereof after extraction can be omitted.
In foundation works or the like in the field of construction and engineering work, there are also various problems in the art due to the friction between foundation works or various substrates and the ground (soil) in the caisson construction method or pipe jacking construction method for laying foundation structures and various substrates (tanks, water storage tanks, Hume pipes, steel pipes, steel pipe piles, etc.) underground.
For example, there is the problem that foundation structures laid underground are damaged by the friction (negative friction) between the foundation structure surface and the surrounding ground in case of ground subsidence in the surroundings, for instance.
In the case of a caisson construction method wherein a tanks is sunk underground by digging out the earth and sand from below the tank, the problem is encountered that since no shoring walls are used, the earth pressure is exerted from the ground on a side of the tank on the tank side during the tank sinking procedure, whereby the tank becomes extremely difficult to sink down.
On the other hand, in the case of a pipe jacking construction method, for instance, construction work is generally carried out while pouring a lubricant (e.g. bentonite/water mixture) around the substrate since when the friction between the substrate (e.g. steel pile) and the soil is great, it is difficult to push the substrate ahead. However, such lubricant has problems; for example, it is necessary to make a line for conveying the lubricant, hence a site and labor therefor is required; the lubricant may reduce the strength of the surrounding ground, and the lubricant should be subjected to post-treatment.
For solving these problems, various means of solution have so far been investigated.
Thus, for example, JP Kokai Publication Hei-04-23514 proposes the so-called negative friction cut construction method which comprises inserting a specific film constitution comprising a film (for adhesion to a foundation structure)/lubricant (e.g. oil)/film (on the soil side) between the foundation structure and soil to thereby make it possible to reduce the friction between the foundation structure and soil even in soil poor in water. In this form of working, however, it is a fatal defect that when the foundation structure is first laid underground by a caisson construction method or pipe jacking construction method, for instance, the above film constitution peels off during laying (driving), hence any sufficient or lasting friction reducing effect can no longer be produced. Another problem is that, in view of the structure thereof, the film may readily be peeled off by a slight friction before construction work even in the period from application to laying (burying), hence is difficult to handle.
JP Kokoku Publication Hei-06-39784 proposes that a water-in-oil type water-swellable polymer particle emulsion or an aqueous dispersion thereof be applied in advance to a foundation structure such as a pile to thereby make it possible to reduce the friction between the foundation structure and soil. In this mode of working, too, it is a fatal defect that when the foundation structure is first laid by a caisson construction method or pipe jacking construction method, for instance, the film formed may readily be peeled off during laying. Furthermore, after application to the foundation structure, the film formed by the above emulsion or aqueous dispersion may readily peel off from that foundation structure upon contact with the surroundings, hence any sufficient or lasting friction reducing effect can no longer be produced, like in the above case, and thus is difficult to handle.
On the other hand, JP Kokai publication Sho-63-27619 describes a technique comprising laying underground a foundation structure coated with a mixture composed of a water-swellable powder (e.g. gelatin, agar)/a film-forming, water-absorbing resin (polyvinyl butyral)/an organic solvent; after laying, the coat film swells by absorbing water in the soil and reduces the friction between the foundation structure and soil.
This method, however, is disadvantageous in {circle around (1)} that the balance between the swelling rate and strength of the water-absorbing resin is poor and {circle around (2)} that the balance between the adhesiveness of the binder resin to the steel material and the film strength is also poor (weak adhesivenss and high film strength), hence {circle around (1)} coat film is readily peeled off from the foundation structure during laying (no coat film remains after laying underground, hence no sufficient friction reducing effect can be produced), and {circle around (2)} the film strength after swelling is not sufficient and the friction reducing layer (swollen layer) shows no sustained release property, more concretely there is no sustained friction reducing effect produced, when it is used in a caisson construction method or pipe jacking construction method or the like.
In JP Kokai Publication Sho-58-191816, there is disclosed a method of preventing the bearing pile negative friction in positioning of a bearing pile which method comprises disposing a resin layer of a resin capable of swelling upon absorbing water between the bearing pile and the surrounding ground to thereby form a layer resulting from water absorption and swelling of the above resin layer and, in the example section, the use of an ethanol solution of polyvinyl alcohol or a paste-like polypropylene glycol together with a water-absorbing swelling resin is disclosed. However, it has a problem, namely the water-absorbing resin may not swell adequately or the water-absorbing resin may be peeled off from the substrate surface in the step of driving the substrate into the ground. In the case of foundation work, substrates are driven into the ground in many instances and, therefore, there is room for investigation in search of one capable of producing sufficient effects in these fields of application.
The JP Kokai Publication Hei-11-241339 discloses a surface treatment agent to be caused to adhere to the surface of a member to be buried for the purpose of preventing the adhesion between the member after burying and the hydrate of a hydraulic composition in a structure constituted of at least the buried member and the hydrate of the hydraulic composition which agent comprises a water-swellable resin and an alkaline water-soluble resin having an acid value of not less than 15 mg KOH/g. The use of this surface treatment agent makes it possible to prevent the adhesion between the substrate surface and hydraulic composition and thereby improve the efficiency of foundation work and so on. However, there is no disclosure at all about the application of such agent to the substrate surface results in prevention of the adhesion between substrate surface and ground (soil) and/or reduction in friction therebetween. In addition, there is room for contrivance for allowing the water-absorbing resin to swell more adequately and making the coat film formed from the surface treatment agent to be less peelable from the substrate surface in the step of driving the same into the ground, for instance, in preventing soil adhesion and reducing the friction. In other words, there is room for contrivance for coping with various work methods and work conditions and thereby enlarging the range of application. JP Kokai Publication 2000-44973 discloses a covering material for covering a temporary work which comprises a sheet-like material and a resin layer containing an alkaline water-soluble resin formed thereon. Such covering material, too, has room for contrivance for coping with various work methods and work conditions and thereby still further enlarging the range of application.
JP Kokai Publication Hei-04-122781 discloses a water-swellable coating composition comprising a water-swellable substance, a thermoplastic elastomer, a filler, a surfactant, an antifungal agent and a solvent. JP Kokai Publication Hei-03-157455 discloses a salt-resistant, water-swellable material which comprises a dispersion of a water-absorbing resin obtained by polymerization of a monomer composition comprising a specific sulfonic acid group-containing unsaturated monomer as an essential component in the presence of a crosslinking agent in a base material comprising a thermoplastic resin and/or a rubber. In JP Kokai Publication Sho-60-168653 discloses a method of reducing the negative friction of a pile which comprises providing a layer mainly composed of a macromolecular material soluble or decomposable in water or alkaline water or a layer comprising the same material as a binder around the pile. Further, JP Kokai Publication Sho-49-71712 discloses a method of sinking a caisson which comprises filling the gap between a structure constructed on the ground and the surrounding ground as formed in the step of digging the ground portion below the structure to sink down the same with a lubricating liquid such as a bentonite slurry or heavy water and allowing the structure to sink with a sheet inserted between the lubricating liquid and surrounding ground. And, JP Kokai Publication Hei-05-118190 discloses a lubricant for the pipe jacking construction method which comprises a highly water-absorbing resin prepared by causing clay and a water-soluble macromolecular substance to be included therein. These technologies, however, have room for contrivance for coping with various work methods and work conditions in a simple and adequate manner to thereby produce the desired effects satisfactorily and efficiently.
In JP Publication Kokai Hei-04-231514, there is disclosed a method of laying a foundation structure underground which comprises carrying out, at least once, the step comprising disposing a lubricant material first on one sheet and then placing another sheet on the lubricant material-carrying surface of the first sheet, adhering the thus-formed lubricating sheet to the foundation structure and laying this foundation structure in the ground. However, such a method has room for contrivance for simplifying the same, for example by applying a coating in advance to the surface of a foundation structure or the like. There is also room for contrivance for coping with various work methods and work conditions to thereby enlarge the field of application.
In JP Kokai Publication Sho-63-165615, there is disclosed a method of reducing the frictional resistance by means of a water-swellable film formed by forming a film on the surface of an object to be laid underground by applying thereto a volatile film-forming resin and a highly water-absorbing resin and allowing the highly water-absorbing resin to absorb water and swell. However, such a method is intended for the recovery of steel materials and the like by extracting them from the earth and sand after back filling but is not intended for preventing the adhesion between the substrate surface and ground (soil) or reducing the friction; another problem is that since the volatile film-forming resin forming the water-swellable film is not dissolved in or swelled with water but permeates water to thereby allowing the water-swellable resin to swell, the swelling capacity of the water-absorbing resin is restricted due to the low hydrophilicity of the water-swellable film.
JP Kokai Publication Hei-04-16618 discloses a method of extracting a temporary work steel material inserted into a cement-based self-curing liquid composition after curing of the composition which comprises the step of applying an acrylic resin to the surface of at least that portion of the temporary work steel material which is inserted into the cement-based self-curing liquid composition prior to insertion thereof into the cement-based self-curing liquid composition, wherein the acrylic resin has an acid value sufficient to make the same soluble in an alkali and comprises a mixture of an acrylic emulsion and an aqueous styrene-acrylic resin solution differing in acid value in specified proportions. This method, however, is intended to reduce the friction between the substrate, which is a temporary work steel material, and the product of curing of a cement mortar or the like but is not intended to prevent the adhesion of the substrate surface and ground (soil) or reduce the friction therebetween. The method has another problem that since the peelable layer formed on the temporary work steel material by the acrylic resin contains no water-absorbing resin, the water-absorbing resin-due effects cannot be produced, hence the soil adhesion-preventing and friction reducing effects will not be sufficient.
JP Kokai Publication Hei-11-21473 discloses a water-repellent coating comprising, as main constituents, a solvent-insoluble powder, a solvent-soluble binder resin and a solvent, wherein the powder has a particle size of not less than 0.03 xcexcm. JP Kokai Publication Hei-09-221630 discloses a coating composition comprising a coating containing a reaction-curable organic resin and a hydroxyl-containing polysilsesquioxane the side chain organic groups of which are each composed of a specific substituent and a specific hydroxyl-containing group and the main chain terminal groups of which are trialkylsilylated as incorporated therein. JP Kokai Publication Hei-08-26177 discloses a method of reducing the frictional resistance in water which comprises admixing resin with a powder the surface of which is covered with functional groups capable of reducing the surface energy as a result of binding of a silane coupling agent, typically a fluorine compound, to hydroxyl groups on the powder particle surface at least via siloxane bonding and applying the resulting mixture to the substrate surface. JP Kokai Publication Hei-09-39147 discloses a water-absorbing composite comprising a water-absorbing sheet whose constituent water-absorbing polymer is to be directly fixed onto a substrate and which is at least partly sutured. Further, JP Kokai Publication Hei-02-49079 discloses a coating composition comprising a silyl group- and polysiloxane group-containing vinyl polymer having at least one specific polysiloxane group in each molecule. And JP Kokai Publication Hei-05-271572 discloses a coating composition for forming nonstaining coating films which comprises 10 to 40 parts by weight of a synthetic resin emulsion to constitute a coating resin fraction, 1 to 10 parts by weight of a water-soluble resin and 20 to 90 parts by weight of water. However, these technologies have room for contrivance for enabling them to produce satisfactory effects in using them to prevent the adhesion between the substrate surface and ground (soil) and/or reduce the friction therebetween.
As discussed hereinabove, any good friction reducing agent is not available in the art that can be used in the negative friction cut construction method, caisson construction method and pipe jacking construction method for foundation structures, will seldom peel off in the step of laying the structures underground irrespective of method of laying, can perform the friction reducing function after (during) structure laying and further can provide a friction reducing agent in a sustained manner (sustained release), more concretely can producing a lasting friction reducing effect.
In view of above-mentioned state of the art as mentioned above, it is an object of the present invention to provide a friction reducing coating for engineering works which {circle around (1)} can be applied to substrates to be buried underground in a simple and easy manner, {circle around (2)} gives a friction reducing coating film for engineering work that will not wholly peel off from the substrates in laying the substrates underground by the soil adhesion-preventing construction method or negative friction cut construction method, caisson construction method or pipe jacking construction method without being affected by the method of laying (although the swollen layer occurring partly on the surface may be peeled off in the step of laying while performing the function of the friction reducing coating for engineering works), {circle around (3)} when used for preventing the adhesion between the substrate surface and ground (soil), reduces the adhesiveness between temporary work steel materials and the surrounding ground in the step of extracting the steel materials and thus allows almost no soil adhesion to the temporary work steel materials during and after extraction without markedly producing such adverse effects as pulling up the surrounding ground, with the result that the space after extraction of the temporary work steel materials can be minimized (the volume of the space being almost the same as the volume of the temporary work steel materials themselves), hence the amounts of the necessary agent(s), earth and sand required for post-treatment (back-filling) can be minimized and {circle around (4)} when used for reducing the friction between the substrate surface and ground (soil), allows the coating film surface to swell by absorbing the water given in advance or absorbed from the ground after driving into the ground or during the caisson construction method or pipe jacking construction method and thus can provide the swollen (friction reducing agent) layer to the interface between the substrate and soil in a sustained manner and can cope with soils of differing nature when the sustained release and other properties are modified according to the hydrophilicity of the binder resin, the coating film thickness and so on.
Another object of the invention is to provide a soil adhesion-preventing sheet pile or steel tubular pipe wherein the above-mentioned friction reducing coating for engineering works applied thereto in advance, and, a soil adhesion-preventing construction method which comprises using the above-mentioned friction reducing coating for engineering works and/or the above-mentioned soil adhesion-preventing sheet pile or steel tubular pipe and further provide a negative friction cut construction method for foundation structures which comprises using the above friction reducing coating for engineering works and thus can cut the friction between a foundation structure after laying underground and the surrounding ground and reduce the influences of changes in the surrounding ground on the foundation structure as well as a caisson or pipe jacking construction method which comprises using the above friction reducing coating for engineering works and can reduce the friction between the substrate and soil while minimizing the influences on the surrounding ground and thus can markedly improve the speed and efficiency of construction work.
To solve the above-mentioned prior art problems, the present inventors studied intensively in search of a soil adhesion-preventing construction method which prevents adhesion between substrate surface and ground (soil) and a friction reducing coating for engineering works which will well adhere to substrates and can provide a friction reducing layer in a sustained manner over a necessary period (in the case of caisson or pipe jacking construction method, during working, namely during laying or burying or, in the case of negative friction cut construction method, over a long period after laying) or, in other words, can maintain the friction reducing effect continuously, without being wholly peeled off in a short period of time.
As a result, they found that the above problems can be solved by applying a friction reducing coating for engineering works comprising a water-absorbing resin (a), a hydrophilic binder resin (b) which has an acid value of 40 mg KOH/g to 500 mg KOH/g and a solvent (c) as essential components in advance on the substrate in accordance with a specific formulation. Such and other findings have now led to completion of the present invention.
By employing the above constitution, it is now possible to provide a friction reducing coating for engineering works which can be used by applying to various substrates and the like in various methods of construction work, for example by applying in advance to temporary work steel materials to be buried in the ground to thereby produce the soil adhesion preventing effect, by which the adhesion between the substrate surface and ground (soil) is prevented, and/or produce a sustained friction reducing effect in the step of laying as well as after laying or, in other words, produce a lasting friction reducing effect. Further, a soil adhesion-preventing sheet pile or steel tubular pipe wherein the friction reducing coating for engineering works has been applied thereto in advance as well as a construction method for various substrates in which the above friction reducing coating for engineering works is used can be provided. The above-mentioned construction method is concretely a method of laying or burying and concrete examples thereof are the soil adhesion-preventing construction method for temporary work steel materials and the like and the negative friction cut construction method for underground structures. The above friction reducing coating for engineering works can also be adapted to the caisson construction method or pipe jacking construction method.
Thus, the present invention provides a friction reducing coating for engineering works comprising a water-absorbing resin (a), a hydrophilic binder resin (b) and a solvent (c) as essential components,
wherein said hydrophilic binder resin (b) has an acid value of 40 mg KOH/g to 500 mg KOH/g.
The invention also provides a soil adhesion-preventing sheet pile or steel tubular pipe
wherein the above friction reducing coating for engineering works has been applied thereto.
The invention further provides a soil adhesion-preventing construction method for the prevention of ground (soil) adhesion to a substrate surface
which comprises utilizing the above friction reducing coating for engineering works and/or the above soil adhesion-preventing sheet pile and/or steel tubular pipe.
The invention finally provides a negative friction cut construction method, caisson construction method or pipe jacking construction method
which comprises utilizing the above friction reducing coating for engineering works.